Reconstructing glacier-based climates of LGM Europe and Russia – Part 3: Comparison with previous climate reconstructions

Abstract

Abstract. Understanding past climates using GCM models is critical to confidently predicting future climate change. Although previous analysis of GCM simulations have shown them to under calculate European glacial temperature anomalies (the difference between modern and glacial temperatures) such analyses have focused primarily on results from glacial simulations alone. Here we compare glacial maximum GCM results with the palaeoenvironment derived from glacier-climate modelling. The comparison confirms that GCM anomalies are not large enough, and that this is due to modern conditions that are modelled too cold and glacial temperatures that are too warm. The result is that GCM results, if applied to a glacier mass balance model, over predict the extent of glaciers today, and under calculate their extent at the last glacial (as depicted in glacial geological reconstructions). Effects such as seasonality and model parameterisation change the magnitude of the under calculation but still fail to match expected glacial conditions.

Depositional environments and diagenesis of a carbonate till from a Quaternary paleoglacier sequence in the Southern Velebit Mountain (Croatia)

“…During the Last Glacial Maximum (LGM), the ELA in Velebit Mountain has been estimated to be in an elevation range of 1217-1300 m asl (Belij, 1985;Bognar and Faivre, 2006) based on Höfer's method of snow-line determination (Höfer von Heimhalt, 1879). Despite more accurate methods to calculate paleo-ELAs (Nesje, 2007), this reported value for the ELA during the LGM is in agreement with regional paleo-ELAs modeling (Allen et al, 2008). The relative accuracy of these results is confirmed by regional studies of paleo-ELAs during the LGM in mountain paleoglaciers of southern Europe, at comparable latitudes (b 4°difference) and with a similar climate context, and are in an elevation range of 1300-1750 m asl (e.g., Kuhlemann et al, 2008;Milivojević et al, 2008;Vieira, Fig.…”

Reconstructing glacier-based climates of LGM Europe and Russia – Part 2: A dataset of LGM precipitation/temperature relations derived from degree-day modelling of palaeo glaciers

“…Details of the DDM, meteorological baseline, data transformations and verification of the methodology can be found in Allen et al (2007b). Details of the transformation required to make the INQUA LGM glacier dataset compatible with the other input data have been detailed in this paper.…”

“…This dataset will enable glacial-geological evidence to contribute to our understanding of the European climate at the continental scale (Allen et al, 2007b). Moreover this work has developed and tested a new and simple method which is transferable to other regions of the world; the appropriate glacial-geological data for the rest of the world required by the glacier-climate model are available in Volumes II and III of the INQUA Quaternary glacier dataset (Ehlers and Gibbard, 2004b;Ehlers and Gibbard, 2004c).…”

“…7 in Kageyama et al, 2001). Therefore, positive precipitation anomalies were included to ensure that the dataset did not require extrapolation to be compared with alternative LGM climate reconstructions (Allen et al, 2007b).…”

Rationalization of Altitudinal Precipitation Profiles in a Data-Scarce Glacierized Watershed Simulation in the Karakoram

“…= water equivalent) and T s is the mean temperature in the summer (June-August) at the ELA (˝C). The summer season temperature-index method has been widely used to calculate ELA climates and glacial melt [46][47][48][49]. Here, T s was calculated from the observed summer temperature at the Taxkorgan Meteorological Station via TLAPS.…”